Aircraft engine and gun assembly



l Sept 8, 1936. M. BIRKIGT 2,053,691

AIRCRAFT ENGINE AND GUN ASSEMBLY Filed March l5, 1934 Patented Sept. 8, 1936 Pn'r'r-:N'ila ortie AIRCRAFT ENGINE AND GUN ASSEMBLY Marc Birkgt, Bois-Colombes, France Application March 15, 1934,-Serial No. '115,714 In France April 15, 1933 4 Claims. (Cl. 89--37) The invention relates tostructures including, on the one hand an aircraft engine driving a propeller shaft, for example through reduction gears, said shaft being offset relatively to the crankshaft of the engine, and, on the other hand, a

gun firing through said propeller shaft.

The object of the present invention is to provide an improved-structure of that kind.

According to the present invention, the barrel of the rearm extends ooaxially throughout the propeller shaft and said barrel is supported by the frame carrying the propeller shaft with a lsuidicient clearance to permit expansion. -Furthermore means are provided for preventing leakage of lubricant at the point where the barrel of the gun passes through said frame.

The invention also includes other features which will be referred to in detail below.

A preferred embodiment of the invention will be hereinafter described with reference to the accompanying drawing in which:-

Fig. 1 shows diagrammatically, partly in section, an assembly constructed according to the invention and includingA a machine gun.

Fig. 2 shows on a larger scale a detail of the foregoing figure.

It will be assumed in the following description that the machine gun is tted on an aeroplane engine.

3o The engine properly speaking is of any suitable type. For example it comprises two rows of cylinders arranged in V form and carried by a common crankcase a.

This engine is provided with a reduction gear,

35 for example a spur gear connecting the crankshaft to a propeller shaft b the axis of which passes between the rows of engine cylinders.

This propeller shaft is provided with an axial bore. through which can `be inserted the barrel of 4 the machine gun above referred to.

This gun is arranged in any suitable way so that when its barrel c is engaged in the bore of the propeller shaft, the said gun is located in the free space left bythe various parts of the engine.

-45 In order to support the gun in place near its muzzle there is provided inthe frame d which supports the propeller shaft, or in a member e mounted in this frame, an aperture f in which the barrel of the gun can be located with a suicient clearance to permit expansion under the effect of the heat resulting from the firing.

Furtherjmeans are provided for preventing the lubricant which serves to lubrcate the DIO- 55 peller shaft and the reduction gear from escaping from the casing at the point where the barrel of the gun enters said casing.

These means advantageously consist of an arrangement of the kind now utilized for preventing losses of lubricant at the point where 5 a rotating shaft leaves a casing, for example by a kind of turbine of which one element rotates near the walls of a\xed element, at least one of these elements having helicoidal grooves running in such direction that when the shaft 10 rotates in the normal direction, the lubricant which tends to escape is forced by the said grooves towards the interior of the casing.

To this end, for example, the portion e carries a tubular rabbet g having either a cylindrical eX- 15 ternal wall adapted to be engaged with a very small clearance (sufficient however in order to prevent contact in any case), in a housing h, also cylindrical, provided on the inner face of the rear end of the propeller shaft, or having a cy- 2G lindrical internal wall adapted to enclose the said rear end of the propeller shaft which is also made cylindrical, with a similar clearance.

At least one of the said cylindrical walls is provided with helicoidal grooves i and in the case 25 where rabbet gis inside the propeller shaft there is advantageously provided on said rabbet g an annular groove i adapted to receive the lubricant forced back by the helicoidal grooves i, a passage being provided for the return of this lubricant to the crankcase.

In order to support the gun in place near the breech the engine advantageously comprises at its rear part a support ,1c to which can be connected one of the fixed members at the rear part of the gun.

This support lc is, for example, given the form of a. fork and the gun is provided with a corresponding projection adapted to be connected to the said fork by a spindle or pin l which makes the disconnection of the arm particularly simple.

'I'he operation and the advantages of this assembly will be sufiiciently obvious from the foreging for it to be unnecessary to enter into any complementary explanation in regard thereto.

The invention is not limited to the particular constructions described, since variations can be made. withi1i"'the scope of the accompanying claims. Thuaiuid-tightness between the propelIer-carrying frame and the barrel of the gun can be ensured through any other suitable arrangement.

What I claim isz- 1. In combination, an aircraft engine, a bearing member xedly mounted with respect to said engine, a hollow propeller shaft having a portion extending within and supported by said bearing member, a gun having a barrel extending into said propeller shaft portion, means to support said gun barrel in said bearing member at the rear of said propeller shaft portion with suicient clearance to permit expansion of the barrel when heated, and means to prevent the passage of lubricant from the outside of the propeller shaft portion to the interior thereof, said last means including a portion of said bearing member exclearance to permit 4expansion of the barrel when heated, and means to prevent the passage of lubricant'from the outside of the propeller shaft portion to the interior thereof, said last means including a portion of said bearing member extending into the rear end of said propeller shaft portion, having an external surface opposite the internal surface of said hollow propeller shaft portion, and angularly positioned grooves on the surface of said bearing member portion.

3. In combination, an aircraft engine, a bearing member xedly mounted with respect to said lubricant from the outside of the propeller shaft portion to the interior thereof, said last means including a portion of said bearing member extending into the rear end of said propeller shaft portion, having an external surface opposite the internal surface of said hollow propeller shaft portion, and angularly positioned grooves on the surface of said bearing member portion, said bearing member having an annular oil holding groove at the rear end of said propeller shaft portion.

4. In combination, an aircraft engine, a bearing member iixedly mounted with respect to said engine, a hollow propeller shaft having a portion extending within and supported by said bearing member, a gun having a barrel extending into said propeller shaft portion, means to support said gun barrel in said bearing member at the rear of' said propeller shaft portion with sucient clearance to permit expansion of the barrel when heated, a portion of said bearing member extending into the rear end of said propeller shaft portion, and cooperating means on said shaft and the bearing member portion operative through relative rotary movement therebetween to prevent the passage of lubricant from the outside of the propeller shaft portion to the interior thereof.

. MARC BIRKIGT. 

